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Differentiating Crohn's disease from intestinal tuberculosis
Saurabh Kedia1, Prasenjit Das2, Kumble Seetharama Madhusudhan3
1Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi 110029, India. dr.saurabhkedia@aiims.edu.
Insights
Differentiating Crohn's disease and intestinal tuberculosis remains challenging. New models show promise, but definitive diagnosis often still requires an anti-tubercular therapy trial, delaying treatment for Crohn's disease.
Area of Science:
- Gastroenterology
- Infectious Diseases
- Diagnostic Imaging
Background:
- Distinguishing Crohn's disease (CD) from intestinal tuberculosis (ITB) is a clinical challenge, particularly in developing nations with high ITB prevalence and rising inflammatory bowel disease burdens.
- While clinical, endoscopic, histologic, and radiologic features differ, definitive diagnostic markers for ITB (caseation necrosis, positive acid-fast bacilli smear/culture, necrotic lymph nodes) have limited sensitivity.
- Existing multi-parametric predictive models for differentiating CD and ITB suffer from complexity, small sample sizes, and lack of external validation.
Purpose of the Study:
- To review current diagnostic modalities for differentiating Crohn's disease and intestinal tuberculosis.
- To highlight the limitations of existing diagnostic criteria and predictive models.
- To discuss emerging parameters and the persistent need for improved diagnostic accuracy.
Main Methods:
- Review of clinical, endoscopic, histologic, microbiologic, and radiologic features differentiating CD and ITB.
- Analysis of the sensitivity and limitations of exclusive diagnostic markers for ITB.
- Evaluation of multi-parametric predictive models, including recent advancements like Bayesian meta-analysis and CT-based scores.
- Discussion on the role and limitations of therapeutic anti-tubercular therapy (ATT) trials in diagnosis.
Main Results:
- Exclusive diagnostic features for ITB (caseation, AFB positivity, necrotic lymph nodes) exhibit poor sensitivity.
- Current predictive models are complex and lack broad validation.
- Emerging parameters like T-regulatory cell enumeration and updated CT scores offer potential improvements.
- Therapeutic ATT trials are often required but delay CD diagnosis and carry risks.
Conclusions:
- Accurate differentiation between CD and ITB remains difficult, necessitating improved diagnostic tools.
- Reducing reliance on empirical anti-tubercular therapy trials is crucial for timely Crohn's disease diagnosis and management.
- Further research and validation of novel diagnostic parameters are needed to enhance differentiation accuracy.
Abstract:
Differentiating Crohn's disease (CD) and intestinal tuberculosis (ITB) has remained a dilemma for most of the clinicians in the developing world, which are endemic for ITB, and where the disease burden of inflammatory bowel disease is on the rise. Although, there are certain clinical (diarrhea/hematochezia/perianal disease common in CD; fever/night sweats common in ITB), endoscopic (longitudinal/aphthous ulcers common in CD; transverse ulcers/patulous ileocaecal valve common in ITB), histologic (caseating/confluent/large granuloma common in ITB; microgranuloma common in CD), microbiologic (positive stain/culture for acid fast-bacillus in ITB), radiologic (long segment involvement/comb sign/skip lesions common in CD; necrotic lymph node/contiguous ileocaecal involvement common in ITB), and serologic differences between CD and ITB, the only exclusive features are caseation necrosis on biopsy, positive smear for acid-fast bacillus (AFB) and/or AFB culture, and necrotic lymph node on cross-sectional imaging in ITB. However, these exclusive features are limited by poor sensitivity, and this has led to the development of multiple multi-parametric predictive models. These models are also limited by complex formulae, small sample size and lack of validation across other populations. Several new parameters have come up including the latest Bayesian meta-analysis, enumeration of peripheral blood T-regulatory cells, and updated computed tomography based predictive score. However, therapeutic anti-tubercular therapy (ATT) trial, and subsequent clinical and endoscopic response to ATT is still required in a significant proportion of patients to establish the diagnosis. Therapeutic ATT trial is associated with a delay in the diagnosis of CD, and there is a need for better modalities for improved differentiation and reduction in the need for ATT trial.